1. Field of the Invention
This invention relates to a hearing protective earplug for controlling communication between the eardrum and the outside of the ear. In particular, the invention is specifically directed to a hearing protective earplug having selective attenuating characteristics to protect against impulse noise while allowing normal conversation in one mode of operation, and in the second mode of operation providing for high attenuation of all sounds between the outside of the ear and the eardrum.
2. Prior Art
The external sounds directed to the eardrum are generally comprised of a mixture of different sound wave frequencies and different intensities of these sound wave frequencies. It is desirable to control the exposure of the ear to waves of high sound pressure level intensities so as to prevent any temporary or permanent hearing loss. For example, sound of varying frequencies can have high intensity to thereby ultimately provide damage to the auditory organ and can cause serious hearing problems including hearing loss and even deafness. Various occupations can be subjected to these high intensity noises such as constructor workers, individuals who operate heavy or noisy equipment and those in the military during explosions or the operation of military weapons. At the same time it is often desirable that individuals be able to communicate while at the same time guard against any of these high intensity noises. At other times it may be desirable to completely shut off, as much as possible, any outside sounds if they are continuing on a constant basis.
There have been prior art earplugs that have attempted to provide against these loud impulse noises while at the same time allowing normal conversation and providing for the selective control of the earplug from a position of complete blocking of the ear canal to a more selective blocking of the ear canal. One such patent is Falco U.S. Pat. No. 6,148,821 which illustrates an earplug including a separate impulse noise filter member and a rotatable structure for either completely closing off the earplug or for allowing the earplug to allow normal communication while at the same time blocking high impulse noise. The structure of this patent is somewhat complex including numerous parts to achieve the two modes of operation. Another prior art patent that includes this combination of features is Woods U.S. Pat. No. 4,353,364 which encompasses a plug member that can be transferred from one storage opening to another active opening to provide for the selective attenuation in the different modes of operation. This patent also includes a number of individual pieces that together form the structure of the earplug.
There are other patents which operate to provide for the above two modes of operation by using a double-ended plug. One end of the plug is used for complete blocking of sound and the other end of the plug is used for selective blocking of external sounds. This structure can be seen in Hamery U.S. Pat. Nos. 5,936,208 and 6,070,693. The earplug must be removed from the ear canal to go between the two modes of operation
In addition to the above, there are prior art patents that include some but not all of the features of the present invention. For example, the Knight U.S. Pat. No. 2,717,596 and de Boer U.S. Pat. No. 4,587,965 provide for earplugs having selective attenuation but do not provide for the plug being completely obscured to prevent the maximum reduction in sound passing to the ear canal. On the other hand, Hocks et al U.S. Pat. No. 281,759 does provide for a plug that can be opened or closed to control the passage or non-passage of sounds to the ear canal but does not provide for the kind of dual mode selective attenuation that is present in the ear protector of the present invention.
There are presently on the market a number of earplugs that include a central shaft and extending therefrom at a nose end that may include at least a single flange. The earplugs are generally composed of a resilient elastomeric material such as synthetic rubber material. The flange element extends outwardly from the nose end of the shaft member and also extends rearwardly from the nose end and is so spaced so as to provide a free annular space between the flange and the shaft. One basic earplug of this type is generally referred to as the V-51R earplug and was developed during the course of World War II in order to provide improved hearing protection to members of the military who were subjected to excessive sound.
In use, this type of earplug is forcibly inserted into the ear canal, thereby at least partially collapsing the rearwardly extending flange element into the underlying free annular space and conforming the flange element into an acoustic sealing relationship with the walls of the ear canal.